With the ever increasing popularity of communication networks such as the Internet, new applications have been introduced, including the so called "electronic commerce". In an exemplary electronic commerce application, e.g. over the Internet, a customer (referred to also as "user", or "first user") transact over the Internet by accessing a vendor's (referred to also as "server" or "second user") site, normally by establishing communication between the customer's client station, typically a P.C., and the vendor's remote server.
Having logged into the desired server site, the customer can select a desired product for purchase. After having paid, on-line, for the desired product or service, the latter is supplied on-line e.g. downloaded, over the network, to the consumer's P.C. or off-line, e.g. by a regular mail service.
The on-line payment over the network poses serious security problems. For accomplishing payment, user privileged information should be provided. By this example, user privileged information includes the customer's credit card number or the identifying code of his/her electronic wallet, or electronic money. (Detailed description of electronic wallet techniques is disclosed, e.g. in U.S. Pat. No. 5,511,121, Efficient Electronic Money; U.S. Pat. No. 5,221,838, Electronic Wallet; and U.S. Pat. No. 4,877,950, Electronic Purse-Device; detailed discussion in electronic money can be found in e.g. U.S. Pat. No. 5,511,121 "Efficient electronic money", U.S. Pat. No. 5,455,407 "Electronic monetary system"). Transaction over the network is, normally, associated also with transaction specific information, and in the latter example, it includes the cost that should be billed for this particular product. The billing may be effected e.g. by crediting loan account or by debiting deposit account.
Thus, if the on-line payment is made by means of a credit card, the communication protocol should assure that the credit card number (constituting user privileged information) that is transmitted over the network is not susceptible to cracking by proficient eavesdropper.
One possible approach of coping with these difficulties is the introduction of the so-called secure electronic transaction (SET) protocol which has been introduced by leading credit card companies (Visa and MasterCard), as well as leading computer companies (Microsoft, IBM and others) that have been consolidated to this end.
Attention is now directed to FIG. 1, illustrating a simplified schematic block diagram of communication protocol, that utilizes the SET standard, between user and vendor.
Thus, for the purpose of on-line payment, the user 1 accesses the vendor 2 over communication network, indicated, generally, by arrow 5, by means of message or messages that include(s) encrypted data indicative of the credit card number (user privileged information) and the amount (transaction specific information) that he/she commits to pay for the specified service or product. The data, in this particular example, is encrypted by means of the SET protocol such that the contents thereof is rendered practically undecipherable for any unauthorized party. In this context the vendor is regarded, of course, as an unauthorized party. The rational behind this approach is to eliminate the possibility of forging, or in other words, to prevent the possibility that the vendor (or any other unauthorized party) will decipher the user privileged information, (i.e. reveal the credit card number) and will use it without obtaining permission from the user.
Turning again to FIG. 1, the vendor forwards the encrypted data to clearing offices 3 and 4 which are regarded as trusted parties. The latter are capable of deciphering the encrypted message (i.e. they hold the appropriate deciphering key(s)), and after ascertaining the user's ID and credit, they affirm (or reject) the transaction and inform on the same to the vendor. Of course, in case of affirmation the user's balance is duly updated. It is absolutely necessary that the trusted party will be temper-proof in order to substantially eliminate any possibility of obtaining the deciphering key(s) and/or any other privileged information held by the clearing office by a third, unauthorized party.
The advantage of using the SET protocol, or the like, is that the credit card number and possibly other user privileged information are retained concealed as the clearing office.
The utilization of the SET protocol and equivalent solutions offer, thus, some kind of security for users who commit electronic commercial transactions over communication networks.
The latter solutions have, however, inherent shortcomings in that unauthorized parties (in this particular case the vendor) hold privileged information of user (albeit in encrypted form). By this particular example the privileged information includes the user's credit card number in an encrypted form. Since there is not available, commercially, a perfect encryption system, there always exists the risk that the distrusted party (by this particular example, the vendor) will manage to decipher encrypted message and extract therefrom the user privileged information or portion thereof and use it improperly.
The above description focused on committing business transaction in the form of acquiring a product or service from remote vendor over communication network. However, the problem of rendering user privileged information susceptible to cracking when transmitted over communication network is shared by many other applications. Typical yet not exclusive examples being user identification system, electronic election system and many others.
It is accordingly the object of the present invention to provide for a system for transacting between user and remote distrusted party over communication network whilst rendering the user privileged information unaccessible to the distrusted party.